The Ticket Of Time

The Premise

There are two worlds separated by more than distance

One exists in Asterfall, a city permanently caught several hours ahead of the others. The Other lies in Vesper, where clocks run behind and the night seems to last a little too long

Nobody knows why the two timelines were separated. Nobody except the mysterious society known as THE HOROLOGICAL CIRCLE. 
Every so often, an impossible phenomenon called The Ticket Of Time occurs.

For exactly one night. The borders between the two time zones collapse. Anyone holding a genuine ticket can cross between them. But only once and when the ticket disappears at dawn, the worlds separate again.

Nico comes from Aster fall, he is an elegant, sharp-tongued academic with a reputation for being impossible to impress. He studies forgotten mythology and secretly investigates The Horological Circle

Than there's Koku from Vesper. He is equally intelligent, infuriating charming and apparently determined to ruin every investigation Nico begins

They call each other rivals. Everyone else calls them a couple

They argue constantly. They steal each other's books. They compete over who can solve a mystery first.